TAB (Testing, Adjusting and Balancing) refers to the three main steps taken in order to achieve correct functioning of the HVAC equipment
(Heating, Ventilation, and Air Conditioning).
TAB usually designates the equipment ''fine-tuning'' procedure, required for the construction of commercial buildings, hospitals and, generally, major infrastructure, more often for clients from abroad than for Italian clients.
Yet sometimes TAB stands for TAB Agencies, i.e. specialized companies employing staff who carry out these services.
Generally, a TAB expert performs measurements on the aeraulic and hydronic circuits of the HVAC systems and adjusts the flow rates as required in order to obtain optimal performance of the summer and winter air conditioning systems.
Balancing is usually based on the design flow rate values, requested by the mechanical designer who drafted the project plan, and the TAB agency submits a written report summarizing the tests and the balancing and highlights the flaws identified while carrying out the TAB activities.
Testing: is the use of specialized tools calibrated to measure temperatures, pressures, rotational speeds, electrical parameters, air and water speed and quantities, for an evaluation of the parts of the system and of the level of performance of the system as a whole.
Adjusting: is the adjustment setting of devices such as air control louvers of the aeraulic circuits and check valves of the hydronic circuits, adjusting the speed/flow rate of fans and pumps, also with respect to the automatic control devices such as thermostats and pressure regulators so as to obtain the system performance required by the design, guaranteeing its efficiency during normal operation.
Balancing: is the system setting, using operation procedures in order to meet the prerequisites. In Italian, adjusting and balancing are almost synonyms, therefore the above-mentioned distinction may seem redundant. We can further clarify the difference by pointing out that, for instance, in a hydronic circuit, ''Adjusting'' is performed by (manually or by electronic adjustment) forcing the automatic valves to the maximum aperture and then the system is ''Balanced'' checking the functions without forcing it.